Republicans served notice they will highlight that Elena Kagan has never served as a judge, she has little time working as a courtroom lawyer, why would the Senate considers her nomination to the U.S. Supreme Court??

Because the Dems want her in...

With practically no judicial and litigation background and only 14 months as U.S. solicitor general, her opponents, is without a record from prior cases with which to criticize President Barack Obama’s second high-court nominee.  Republicans are concerned Kagan’s limited record of scholarly writings may not provide enough information to determine whether they can support her nomination.

Republican Senators speaking out against her nomination weigh heavily this lack of experience;
Senate Republican Leader Mitch McConnell, of Kentucky, said “a lifetime position on the Supreme Court does not lend itself to on-the-job training.” If a nominee doesn’t have judicial experience, “they should have substantial litigation experience,” he said. “Ms. Kagan has neither.”  Arizona Senator Jon Kyl told Kagan at her confirmation hearing that lack of experience might be a handicap in effectively carrying out her duties as the government’s top Supreme Court advocate.
“Thorough academic knowledge, while important, in my view, is no substitute for having done litigation,” Kyl told Kagan in February 2009. The “greatest knowledgeable surgeon” in the operating room “still has to get those fingers working to do the right kind of sewing,” he said.

Then there are her views...like banning military recruiting at Harvard because of the "Don't ask, Don't Tell" policy.
She signed a brief challenging a law that lets the U.S. government withhold millions of dollars in federal aid if a university doesn’t give military recruiters the same access to students as other employers.
The Supreme Court voted 8-0 to uphold the law, rejecting Kagan’s argument.

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